Hydraulic sub-surface pumping unit



R. H. DEITRICKSON HYDRAULIC SUB-SURFACE PUMPING UNIT 6 Sheets-Sheet 1Filed June 28, 1954 LEGEND POWER FLUID ENGINE EXHAUST -1:

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HYDRAULIC SUB-SURFACE PUMPING UNIT Filed June 28, 1954 6 Sheets-Sheet 5amt,

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Roy H. Denrvckson BY 32 @4214 PM AT' 'O R NEYS Nov. 19, 1957 R. H.DEITRICKSON 1 HYDRAULIC SUB-SURFACE PUMPING UNIT Filed June 28. 1954 6Sheets-Sheet z JNVENTOR.

United States Patent HYDRAULIC SUB-SURFACE PUMPING UNIT Roy H.Deitriclrson, Toledo, Ohio, assiguor to The National Supply Company,Pittsburgh, Pa., a corporation of Pennsylvania Application June 28,1954, Serial No. 439,840

Claims. (Cl. 103-46) This invention relates to sub-surface hydraulicpump ing units and more particularly to sub-surface hydraulic pumpingunits of the type employed in deep wells such as oil wells and to such apumping unit which is designed to balance the pressure requirements onboth the up and down strokes and thus permit uniform speed of operationon both strokes as well as uniform loading of the surface equipment fromwhich the working pressure is derived.

Sub-surface hydraulic pumping units of the type referred to are actuatedby power fluid pumped down the well from equipment at the surface to thepumping unit. The power fluid is introduced into a pumping unit enginewhich is connected by a rod to a production pump located at theproduction fluid level. The pumping unit consisting of the engine andpump may be connected to the surface by means of a so-called macaronistring for carrying the power fluid from the surface down to the pump orit may be of the type denominated a free pump which is lowered down thepump tubing without any direct surface connection.

In either case it is preferable that the load on the surface equipmentwhich creates the pressure in the power fluid should remain constantduring the operation of the pump engine whether on an up stroke or on adown stroke. It is also desirable that the speed of operation on bothstrokes be approximately uniform since the operation of the pump andengine valving is improved if there is no tendency of the unit to racein one direction and work slowly in the other.

It is, therefore, the principal object of this invention to provide asub-surface hydraulic pumping unit comprising an engine and a productionpump that is actuated by power fluid pumped from the surface in whichthe pressure and volume of the power fluid are balanced at the samevalues during the up and down strokes.

, It is a further object of this invention to provide a sub-surfacehydraulic pumping unit in which the various areas of the engine andproduction pump which are exposed to power and production fluids are soproportioned as to result in a net load on the power fluid pumping meanswhich remains relatively constant during up and down strokes of the pumpengine.

Other and more specific objects and advantages will be better understoodfrom the specification which follows and from the drawings in which:

Fig. l is a fragmentary vertical sectional View of a free hydraulicpumping unit embodying the invention;

the mechanism being shown during an up stroke.

Fig. 2 is a view similar to Fig. 1 but showing the mechanism during adown stroke. Fig. 3 is a schematic drawing of the mechanism shown inFig. 1 and illustrating the balancing of working or power fluidpressures. i

' Fig. 4 is a view similar to Figs. 1 and 2 but illustrating a closedcircuit, surface connected, hydraulic pumping unit embodying theinvention.

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Fig. 5 is a schematic view similar to Fig. 3 but of the hydraulicpumping unit shown in Fig. 4.

Fig. 6 is a view similar to Fig. 5, describing a pump of the generaltype shown in Fig. 4 but having different proportions.

Fig. 7 is a diagrammatic view in section of valving mechanism suitablefor the control of a hydraulic pumping unit embodying the inventionshown in its up stroke position corresponding to the position of thepumping unit as a whole shown in Fig. 1.

Fig. 8 is a view similar to Fig. 7 but showing the mechanism during adown stroke.

Figs. l-3 illustrate a sub-surface hydraulic pumping unit of the typegenerally known as a free pump, which embodies the invention. Thesub-surface hydraulic pumping unit of the invention is shown in aconventional background comprising a well casing 10 which serves as thewall of the well and encloses a pump tubing 11 and a macaroni string 12,in this case employed for carrying a mixture of production fluid andspent power fluid to the surface. A hydraulic pumping unit embodying theinvention comprises an engine generally indicated at 13 and a productionpump generally indicated at 14. The engine 13 has a piston 15 that isvertically reciprocable in a pump cylinder 16 and is connected by a rod17 to the upper end of a production pump plunger 18. The engine 13 isenclosed in an engine casing 1.9 of diameter somewhat smaller than theinner diameter of the well tubing 11 thus leaving an annular space 2%surrounding the engine casing 19 and leading downwardly to the bottom ofthe pump tubing 11 where it is closed by a conventional gas header andpump seat 21. The engine cas ing 19 is connected to and operativelyintegral with a pump casing 22 and a bottom discharge valve generallyindicated at 23 places the interior of the pump casing 22 incommunication with the annular space 25) surrounding the casing. At thebottom of the pump casing 22 there is located a standing ball valvegenerally indicated at 24. A suitable packer (not shown) is providedbetween the engine casing 19 and the interior of the tubing 11, thepacker being disposed above the engine exhaust openings in a knownmanner.

The rod 17 connecting the engine piston and pump plunger is tubular,having a bore 25, thebottom end of which is closed by a spring pressedrelief valve 26 and which is in communication through radial ports 27with a pocket 28 surrounding the rod 17 between the upper end of theplunger lit; and a shoulder 29 at the upper end of the pump cylinder 22.The rod 17 is sealed by a packing 30 located between the upper end ofthe pump cylinder 22 and the lower end of the engine casing 19.

The bottom of the engine cylinder 16 is connected by radial ports 32 andan annular passageway 31 to valving, hereinafter described, located atthe upper end of the engine 13 for carrying power fluid beneath theengine piston 15. Power fluid for causing a down stroke is admitted intothe engine cylinder 16 above the engine piston 15 by the same valvingwhen a down stroke is to be initiated. When the pressure on the upperand lower sides of the engine piston is equalized the piston moves downdue to the difference in area between the upper and lower surfaces.

Operation of the pumping unit in the up stroke with the connectionsestablished as illustrated in Figs. 1 and 7 is as follows: The enginevalve illustrated in Figs. 7 and 8 and shown in Fig. 7 in the positionassumed during an up stroke of the pump, is connected by a passageway 33to a surface source of high pressure working fluid. The passageway 33opens into a valve chamber generally indicated at 34 in which is locateda vertically reciprocable valve body generally indicated at 35 andcomprising a floating valve collar 36.

The operation of the valve 35 and collar 36 is described in detail andclaimed in my copending application Serial No. 297,473, now Patent No.2,682,257 issued June 29, 1954. The operation of the valving mechanismwill, therefore, be described only briefly in the instant application.

In Fig. 7 it will be seen that the annular passageway 31 is acontinuation of the valve chamber 34. With the valve body 35 in theposition of Fig. 7 a spool valve shoulder 37 on the body 35 seats in anannular seat 38 to prevent the high pressure working fluid from flowingupwardly through the chamber 34. At the same time the position of thevalve body 35 as shown in Fig. 7 connects a radial passageway 39 in thebody 35 to a valving chamber 40 and the chamber 40 is connected by aseries of radially extending escape ports 41 to the annular space 21)surrounding the pump and engine housing. The radial passageway 39 in thevalve body 35 intersects a longitudinal bore 42 through the body 35 andthrough the bore 42 is in communication with a space generally indicatedat 43 above the piston 15 in the engine cylinder 16.

Power fluid flowing down the annular passageway 31 flows through theports 32 into an annular chamber 44 surrounding the rod 17 and locatedbetween a bottom 45 of the cylinder 16 and the undersurface 46 of theengine piston 15. Power fluid acting against the shoulder forming theundersurface 46 of the engine piston 15 drives the engine piston 15upwardly pulling upwardly on the rod 17 and the pump plunger 18. Thiscreates suction in an intake chamber 4'7 inside the pump casing 22 anddraws production fluid into the chamber 47 displacing the standing valve24 from its seat and filling the chamber 47. During this intake stroke,exhaust engine oil is discharged from the space 43 in the enginecylinder 16 above its piston 15 through the bore 42 and space 43, thechamber 40, the ports 41 and into the annular passageway 20 where itflows downwardly around the exterior of the engine casing 19 and pumpcasing 22.

The engine exhaust fluid flows down the annular passageway 20 forcingproduction fluid in that passageway downwardly and blending with it atthe bottom of the tubing just above the seat 21 whence it passesoutwardly through a connection 48 to the macaroni string 12 and to thesurface. During this up stroke the static head of the fluid in theexhaust fluid annular passageway 20 holds the bottom discharge valve 23in its seat.

During an up stroke the volume of the pocket 28 (Fig. l) is, of course,decreased, compressing any gas which may be located therein. Thepressure in the gas in the pocket 28 is prevented from reaching too higha level by the spring pressed relief valve 2.6 which opens to vent theinterior of the rod 17 and the pocket 28 as the gas pressure thereinbuilds up. Gas vented by the relief valve 26 is exhausted through thebottom of the pump plunger 18 into the chamber 47.

Figs. 2 and 8 illustrate the position of the pump parts and the valvingduring a down stroke. The valving mechanism is changed from the positionshown in Fig. 7 to the position shown in Fig. 8 by the pressure createdin the exhaust fluid located in the space 43 as the piston 15 approachesthe limits of its upward stroke. It will be observed in Figs. 7 and 8that a lower tubular extension 49 of the valve body 35 protrudes intothe space 43 and that a small clearance is left, generally indicated at50, around the extension 49 into an annular pocket 51 at the undersideof the main body of the valve 35. A buildup of pressure within thisannular pocket 51 under the conditions and balances of pressure that arecompletely described in the above mentioned copending application,causes the entire valve body 35 to shift upwardly opening the pocket 51into the main valve chamber 34 and unseating the shoulder 37 from itsseat 38; at the same time seating a similar shoulder 52 in an annularseat 53 at the upper side of the chamber 40. This closes the connectionbetween the chamber 40 and the escape ports 41 and establishes aconnection between the passageway 33 to the chamber 40 as shown in Fig.8. Power fluid now flows from the passageway 33 to the chamber 40through the passageway 39 and bore 42 through the valve body 35 and intothe space 43 above the piston 15. The pressure of working fluid on theupper face of the piston 15 overcomes the pressure of working fluid onthe annular underface 46 of the piston 15 and drives the piston 15downwardly.

It will be seen in Fig. 8, however, that the chamber 44 beneath thepiston 15 is still connected through the ports 32 to the annularpassageway 31 and that these spaces are in communication through thechamber 34 with the high pressure fluid line 33. Downward movement ofthe piston 15 therefore results from a balancing of the pressures on theupper and lower faces of the piston 15 and high pressure oil flowsupwardly through the passageway 31 and past cooperating shoulders on theinner wall of the chamber 34, the valve body 35 and the floating valvecollar 36. As the piston 15 moves downwardly all of the high pressurefluid trapped in the chamber 44 flows upwardly through the passageway 31and into the chamber 34 being augmented by additional high pressurefluid from the passageway 33 to displace the piston 15 downwardly. Thereis no discharge of spent or exhaust power fluid from the valving duringthe down stroke.

The action of the floating collar 36 and other elements of the valvemechanism shown in Figs. 7 and 8 and not described herein in full detailis fully explained in the copending application mentioned above.

Downward movement of the engine piston 15 thrusts the rod 17 and pumpplunger 18 downwardly. Pressure on the fluid in the production fluidchamber 47 seats the standing valve 24 at the bottom of the chamber 47and lifts the bottom discharge valve 23 from its seat permittingproduction fluid in the chamber 47 to be exhausted through the dischargevalve 23 and into the production fluid annular passageway 20. Productionfluid in the passageway 20 is forced downwardly to the bottom andoutwardly through the connection 48 in the macaroni string 12 to thesurface.

Bottom reversal of the direction of movement of the piston 15 occurswhen the piston 15 approaches the bottom of its stroke and the rate offlow of the power fluid upwardly through the annular passageway 31 andpast the floating collar 36 drops. When this flow of oil is reducedsufliciently the high pressure oil in the chamber 34 above the collar 36moves the collar 36 downwardly until its lower shoulder 54 engages anopposed shoulder 55 on the valve body 35 and moves the valve body 35bodily downward into the position shown in Fig. 7. A more completeexplanation of this operation appears in the above identified copendingapplication.

With reference now to Fig. 3, it will be seen that the forces acting onthe engine piston 15 and the pump plunger 18 during a down stroke and anup stroke can be demonstrated as being equal so that the same load ismaintained on the power fluid pump which actuates the engine piston 15during both down and up strokes, and the speed of operation will be thesame on both strokes.

The area of the top of the engine piston 15 is indicated by the letter Aand may be, for example, 4 square inches. If the area of the rod 17 (a)is 2 square inches, then the area of the annular surface 35 (x) is 2square inches (A-a or 42). In this particular pumping unit the area ofthe bottom of the pump plunger 18, denominated B, is also 4 squareinches.

During a down stroke (Fig. 2) area A is exposed to power fluid indicatedin the table appearing with Fig. 3 by the letter P. This force is actingdownwardly to prosurface.

duce the down stroke being performed. At the same time, since theunderside of the engine piston 15, i. e., the surface 46, also isexposed to power fluid, the area x is exposed-to power fluid which actsin an upward direction. During a down stroke the bottom of the pumpplunger 18, area B, is exposed to the pressure of the standing column ofproduction fluid leading from the surface of the well. This productionfluid pressure is indicated by the letter p in the table appearing withFig. 3. The net force which must be overcome by the pressure of thepower fluid acting downwardly on the engine piston during a down strokeis the sum of the following pressures: Down area AXP or 4P+Up area x Por 2P+ area B p or 4p. The net down pressure is, therefore, (4P-2P-4p)or 2P-4p.

During an up stroke, power fluid at high pressure is present in thechamber 44 beneath the engine piston 15 and the area x is exposed tohigh pressure. At the same time the area A above the engine piston 15 isvented to the exhaust fluid annular passageway so that the surface A isunder the production fluid column pressure or p. During an up stroke thearea B on the bottom of the plunger 18 is under no pressure at all sincethe plunger is moving upwardly and production fluid is being drawn intothe chamber 47 (Fig. l). The force required there- .for to produce an upstroke is the sum of the upwardly acting force P on the area x or 2Pminus the production fluid column pressure p acting on the area A or 4p.Again the net pressure required to produce an up stroke equals 2P4p.

An identical situation prevails in a surface connected pump such as thepump illustrated in Fig. 4. In Fig. 4 there is shown a well casing 56containing a pump tubing 57 which in turn contains a surface connectedpumping unit comprising an engine indicated at 58 and a production fluidpump generally indicated at 59. The engine 58 has an engine piston 60only fragmentarily shown at the upper end of Fig. 4 which, throughvalving (not shown) is alternately connected to receive power fluid froma power fluid line 61 and to exhaust spent fluid to an engine exhaustline 62. The engine piston 60 is connected to a rod 63 which extendsdownwardly through an engine casing 64 and through an engine cylinder 65therein. The valving (not shown) connects the power fluid lineconstantly to the bottom of the cylinder 65. When the pressure on theupper and lower sides of the engine piston 60 is equalized the pistonmoves down due to the difference in area between the upper and lowersurfaces. When the engine cylinder above the piston is connected toexhaust, the piston moves up under the infiuence of the power fluidbeneath it.

In the form shown the pump plunger 66 and the rod 63 near its lowerportion are made tubular and a traveling ball valve 67 closes and opensthe lower end of the bore thus forming a chamber 68 in the interior ofthe rod 63 and plunger 66. The chamber 68 is connected through ports 69to an upper pump chamber 70 located at the upper end of the productionpump 59. The chamber 70 is ported to an annular production fluidpassageway 71 surrounding the engine casing 64 and leading to the Achamber 72 located between an upper shoulder 73 on the pump plunger 66and the top of a cylinder 74 of the pump SP is vented by ports 75 to thespace surrounding the tubing 57 in the casing 56.

A production fluid chamber 76 is located in the pump 59 beneath theplunger 66 and provided with a standing valve 77 which alternatelyconnects and isolates it from incoming production fluid.

During a down stroke of the pumping unit illustrated in Fig. 4 powerfluid P acts over the area A of the top of the engine piston 60. Thismoves the piston 60 downwardly pushing the rod 63 downwardly and thepump plunger 66 downwardly. Movement of the plunger 66 downwardly liftsthe traveling valve 67 from its seat and 6 seats the standing valve 77.Production fluid passes from the chamber 76 into the bore 68 in theinterior of the rod 63 and plunger 66.

To produce an up stroke the area A above the engine piston 60 is ventedto the exhaust line 62 and power fluid present in the chamber 65 beneaththe piston 60 moves the piston 60 upwardly. This lifts the rod 63, alower integral plunger extension 78 and the pump plunger 66. This upwardmovement seats the traveling ballvalving 67 and lifts the standing ballvalve 77 from its seat. The upward movement of plunger extension 78 intothe chamber 70 displaces production fluid in the chamber 70 forcing itoutwardly through ports 79 into the passageway 71. At the same time theupward movement of the pump plunger 66 draws a new charge of productionfluid into the chamber 76. i i

A pumping unit as illustrated in Fig. 4 and shown diagrammatically inFigs. 5 and 6, is designed for use in a well where a large volume ofproduction is to be maintained. It will be observed that the diameter ofthe pump plungers of Figs. 4, 5, and 6 are larger than the diameters ofthe engine pistons. This permits maximum area on the pump plungers forany given diameter of well tubing with ample space around the enginecasing for the production fluid to move up to the surface. Theadditional force on the smaller diameter engine pistons required toactuate the larger pump plungers and lift the larger volumes ofproduction fluid may be provided by using higher pressure power fluid,or no additional force may be required if the well is shallow and easilypumped.

Reference to Figs. 5 and 6 indicates how two exemplary pumping unitsconstructed in the just described manner are so proportioned accordingto the invention as to result in balanced forces during up and downstrokes. In Fig. 5 the engine piston 60 is shown as having an upper areaA of 4 square inches. The rod 63 is shown as having a minor area a of 2square inches leaving an annular shoulder 80 or area x of 2 squareinches. The plunger extension 78 is connected by a tapered portion 81 tothe rod 63. The plunger extension 78 has an area b of 3 square inches.The projected area of the tapered portion 81 indicated by the letter yis thus ba or 3-2 or 1 square inch. The bottom of the pump plunger 66has an area b of 6 square inches.

Under the conditions outlined with respect to Fig. 5 the net pressure tobe provided by the power fluid is calculated according to the tableshown in connection with Fig. 5 where it is seen that during a downstroke the area A on the top of the engine piston 60 is exposed to highpressure P. The area x of the annular shoulder 80 beneath the enginepiston 60 is, of course, also under high pressure P since the highpressure power oil exists in the chamber 65 during both up and downstrokes. Thus the area A at high pressure P or 4P acts downwardly whilethe area x at high pressure or 2P acts upwardly. At the same time thearea B on the bottom of the pump plunger 66 is under the productionfluid pressure p of the standing column of production fluid and so isthe projected area y of the tapered surface 81. Thus the area B resultsin a pressure equal to 6p tending to move the plunger 66 up wardly andthe area y results in a pressure of 1p tending to move the plunger 66downwardly. The net force is therefore the sum of area A (4P) minus arear (2P) plus area y (lp) minus area B (6p) or 4P-2P+p-6p equals 2P-5p.

During an up stroke area A on the top of the engine piston 60 is exposedto production fluid in the column of the line 62 leading to the surface.Area B during an up stroke is under no pressure at all. Area x is underthe power fluid pressure P producing the upward movement and area y is(as in the down stroke) under the production fluid column pressure p.The net up stroke force required is therefore area x under power fluidpressure or 2P acting upwardly minus area y (1p) downwardly minus area A(4p) acting downwardly or 2P-p--4p equals 2P-5p or the same net forcerequired as during the down stroke.

Fig. 6 illustrates a modified form of the pump shown in Figs. 4 and 5 inwhich the area B of the bottom of the pump plunger 66a is 8 squareinches and thus twice as large as the area A of the engine piston 60a.The dimensions of the rod 63a may be the same as in Fig. 5, i. e., 2square inches, and, for example, the area of the plunger extension 78ashown as 4 square inches (area b) The annular area x is thus 2 squareinches and the annular area y is similarly 2 square inches. Under theseconditions, referring to the table appended to Fig. 6, during the downstroke, power fluid P acts on area A and on area x. Production fluid pacts on areas B and y. The net force thus required to produce a downstroke is area A (4P) minus area x (2P) minus area B (817) plus area y(2p) or 4P-2P8p+2p or a net of 2P 6p.

Similarly during an up stroke area x is exposed to high pressure fluidfor 2P acting upwardly. As explained above there is no pressure on areaB. Area A is subjected to production fluid pressure (4p) actingdownwardly and area y again is subjected to production fluid pressure(217) acting downwardly. The net force therefore is 2P4p 2p or 2P-6p, aswas the case during the down stroke.

Various arrangements and relationships of areas of the several surfacesinvolved may be made within the scope of the invention whereby the loadon the surface equipment producing the power fluid pressure remains thesame during both up and down strokes of a pumping unit embodying theinvention.

Having described the invention, I claim:

1. A sub-surface hydraulic pump that is adapted to be located at theproduction level of a well casing, comprising, a source of high pressurepower fluid, a differential area fluid operated engine piston, a pumpplunger having a rod connected to said engine piston, first valve meansto admit production fluid beneath said pump plunger on its upstroke andto discharge fluid against well head pressure on at least its downstroke, second valve means to admit power fluid beneath said enginepiston to cause an up stroke of said piston and alternately to admitpower fluid above said engine piston at the same pressure to cause adown stroke of said piston, said second valve means including means tocause fluid from beneath said piston to be circulated to the space abovesaid piston during the down stroke and including additional means tocause fluid to be exhausted from above said piston during the up stroke,the relative areas of said upper and lower engine piston surfaces andthe upper and lower surface of said pump plunger being so proportionedthat the sum of the effective areas exposed to power fluid are equal onboth up and down strokes and the effective areas exposed to well headpressure are equal on both up and down strokes.

2. A sub-surface hydraulic pump according to claim 1 in which said pumpplunger has a cylinder with a bottom discharge valve and the productionfluid is admitted beneath said pump plunger during an upstroke wherebyno pressure is exerted on the bottom thereof, and is discharged frombeneath said pump plunger against well head pressure on a down stroke.

3. A sub-surface hydraulic pump according to claim 1 in which the pumpplunger has a traveling valve and production fluid is admitted beneathsaid pump plunger during an up stroke and transferred through said valveto above said plunger during a down stroke, whereby the bottom of saidpump plunger is subjected to the pressure of the production fluid columnto the surface during a down stroke and production fluid is displacedfrom above said plunger during both up and down strokes.

4. A sub-surface hydraulic pump according to claim 1 in which the areaof the upper surface of said engine piston equals the area of the lowersurface of said pump plunger and is equal to twice the cross-sectionalarea of said rod.

5. A sub-surface hydraulic pump that is adapted to be located at theproduction level of a well casing, comprising, a source of high pressurepower fluid, a differential area fluid operated engine piston, a pumpplunger having a rod connected to said engine piston, first valve meansto admit production fluid beneath said pump plunger on its upstroke andto discharge fluid against well head pressure on at least its downstroke, second valve means to admit power fluid beneath said enginepiston to cause an up stroke of said piston and alternately to admitpower fluid above said engine piston at the same pressure to cause adown stroke of said piston, said second valve means including means tocause fluid from beneath said piston to be circulated to the space abovesaid piston during the down stroke and including additional means tocause fluid to be exhausted from above said piston during the up stroke,the relative areas of said engine piston, pump plunger and rod being soproportioned that flow of fluid from above said engine piston plus theflow of fluid from above said pump plunger on an up stroke is equal tothe flow of fluid from beneath said pump plunger on a down stroke.

References Cited in the file of this patent UNITED STATES PATENTS825,950 Weir July 17, 1906 1,848,070 Archer Mar. 1, 1932 2,497,348 EckerFeb. 14, 1950

